Method for treating oils



vMaly 19, 1936. u. B. BRAY METHOD FOR HEATING oILs Filed May 23 1933Patentedl May v19, 1936- UlTED-sTATEs nmrnon Foa :mme ons Ulrlc B. Bray,Palos Verdes Estates, Calif., as-

sgnor 4to Union Oil Company of California, Los eles, Calif., acorporation of California Application May 23, 1933, Serial No. 6l2,4.32v

9 Claims.

The present invention relates to a method for separating asphalt fromoil. More specically, it i relates to a method for separating asphaltfrom asphalt containing ,pils in a plurality of stages,y

A ,o This invention is a continuation, in part, of my co-pendingapplications Serial No. 466,189, led July 7, 1930; SerlalfNo.610,130,'led May 9, 1932 and Serial N0. 659,854, flledMarch-, 1933.

In my co-pending application Serial No.

'10 466,189, Idisclosed a two-stage process for thev separation ofasphalt and wax from crude oils ortopped crudes containing the saine toproduce lubricating oil. In the first stage' of the process,

the asphalt ,andl wax containing/oil was` coml' mingled withta liquefiednormallyrgaseous hy? drocarbon solvent, such as liquid propane, underpressure suicient to maintain the-propane in a liquid state. Thispermitted the-asphalt to` precipitate from -the'solution oi' oil andpropane andsettle to the bottom of the decanter. 'Ihe oil solventsolution was separated from the precipitated asphalt and was thenchilledl by evaporatingV a portion of the propane under reducedpressure. This caused the .wax to precipitate from 1 the solution. Thewax -was separated and then the propane was removed from the remainingoil solvent solution to produce a lubricating oil which wassubstantiallygfree from asphalt and wax.

my -co-pending application Serial No.

m a 610,130, l disclosed a process for the co-precipita- Y tionyofasphalt and wax by means of a liqueed4 normally gaseoushy'drocarbonsolvent, in ,par-

ticular, liquid propane, wherein the asphalt and Vwiso: containing oilwas commingled with the sol- 3.5 vent 'underpressure suillcient tomaintain the solvent in aliquid state. yThe oildissolved in the liquidpropane and the asphalt was thrown outlj oi solution. A portion of theliquid propane was allowed to vaporize under reduced pressure to 40chill themixture' of oil, solvent, wax and asphalt to asu'clently lowtemperature to cause precipitation oi the wax. The ebullition or boilingwhich accompanies the vaporization Vof the liquid propanecaused aviolent, agitation oigthemass and the 'precipitated asphalt acted asnuclear or gathering bodies for the agglomeration o1 the wax as it wasprecipitated at the lower temperature attained. The agglomeratedparticles of waxend asphalt were then separated from the oil solventsolution and the solvent was' removed from the oil. This oil was alubricating oil substantially free from asphalt and wax. l

In the foregoing process, I have observed that the lubricating oilproduced isalso free from the (Cl. 19H-13) Conradson carbon value.v Itis my belief that the presence of these heavy viscous oil fractions inlubricating oils are largely responsible for the y high Conradson carbonvalues or lubricating oil. Such fractionswere thrown out of solution by5 chilling the oil containing both asphalt and waxl and settled-to thebottom of the decanter. In other words, I have discovered that chillingan oil to precipitate wax will also effect precipitation of the heavyviscous oil fractions, which, when 10, separated from.v the oil, willproduce a lubricating oil of lower Conradson carbon value than when suchfractions are retained in the lubricating oil.

In my co-pending application ASerial No. 659,854, I disclosed a processfor the co-precipita- 15 tion of asphalt and heavy viscous oil fractionsfrom asphalt containing residues substantia1ly. free from wax. Suchprecipitation was eii'ected by mixing a liquefied normally gaseoushydrocarbon solvent, in particular, liquid propane, with 20 .thelasphalt containing oil under pressure sufcient to maintain the solventliquid `and then reducing the pressure on the mixture to lpermitevaporation of avportion of the propane which i chilled the oil solventsolution and precipitated 25.` the asphalt and heavy viscous oilfractions from solution. Ihe precipitated mixture was removed from theoil solvent solution and was then heated to vaporize residual propane.The asphalt was recoveredas a mixture of hard bitumen and heavy 30viscous oil fractions.h The oil solvent solution substantially freelfrom asphalt andfheavy viscous 4 so-called stabilizing" methodnowconventional in the natural gasoline industry. They are the Ml overhead`obtained. They are liqueled by compression and cooledin the conventionalmanner and are drawn od into pressure chambers where they are maintainedin a liquid state until used.

A typical` analysis of suchl a fraction is 6.72% 50 ethane, 72.2%propane, 19.91% isobutane and 1.17% normal butane. Such a fraction maybe maintained in a liquid state at a pressure of-125' lbs. persquareinchat atemperature 'of about 55 F: The predominatlng hydrocarbonmember in this mixture is propane `and hereafter when I use the wordpropane or liquid propane" I v am referring to such a fraction.

rtlwiil be observs that by the term Aaspmtlty Iintend to include -suchasphaltic and non-waxy fractions which will separate or precipitatefrom"u asphalt containing oils when these'oils are com- The present inventionis also related to a treatment of asphaltic oils which are substantiallyfree from wax. As stated in my aforementioned co-pending application,Serial No. 659,854 substantially al1 petroleum oils and particularlyasphalt containing oils contain such heavy viscous oil fractionsirrespective of whether they contain wax. It will be observed-that allasphaltic oils contain more or less wax; some contain `large yquantitiesof wax, while others arev substantially 'freebut nevertheless contain a-small quantity.

Thus, such California crude oils as McKittrick, Poso Creek, Coalinga.Summerland and Sunset are typical asphaltic crudes containingveryrlittle wax, while other crudes as Montebello', Kettleman Hills,Santa Fe Springs, Elwood, Torrance and SantajBarbara are classed asmixed base crudes, that is,they contain large quantities of wax as wellas asphalt. Nevertheless, substantially all of these oils contain highymolecular weight bodies whicharel responsible for the high Conradsoncarbon value ofv lubricating oils. In treating oils substantially freeof wax, it is customary to maintain the temperaturesy for separation ofasphalt at approximately atmospheriai. e. about 70 Fl to 80 F. At suchtemperatures, the heavy viscous oil fractions are soluble in the oilsolvent solution and will -not precipitate from sol lution.' My presentinventionfis directed towards removal of such fractions from oils. It isparticularly directed to treatment of asphaltic nonwaxy oils. However,as will be-described below and as has been stated above, vit is alsoapplicable to asphaltic wax containing oils;

By the present invention, I propose to' sepa- `rate the asphalticmaterial in asphalt containing oils substantially free from wax in aplurality of stages.' in particular, in two stages. I have nowdiscovered that I may precipitate and' recover two entirely differenttypes of asphalt, that is,

.a hard asphalt and a soft asphalt, if the prel cipitation by solventsand separation is eifected in :two stages. In one stage of the process,the4 oil containing asphalt is mixed withv aliqueed normally gaseoushydrocarbon solvent under `f pressure suiilcientto maintain the solventinthe liquid state lto precipitate hard asphaltic material and at atemperature of substantially atmospheric, i. e.. about '10 F. to 80 F.The precipitated asphalltic` material is separated from the "oil solventsolution and then the oil solvent solution which has been freed from thehard asphalt is chilled in a second stage to a sufficiently lowtemperature, i. e. about -40 F. to 0 Eto precipitate further quantitiesof asphaltic' mafterial. The character of the asphalt recovered in the'il'rst stage comprises a substantially hard asphalt or substantiallypure bitumen, while the asphaltic material recovered inthe second stagecomprises the heavyviscousoil fractions. aforementioned whicharesoluble'. inthe oill solventsolution 4at atmospheric temperatures;Chilling of -the oil solvent solution;- from which .the hard asphalt hasbeenre'mdved will con'geal vs uch precipitate out of solution:

heavy viscous oil fractionsy and cause 4 them tomingled with liquidpropane or other solvents. Thus, the heavy viscous oil fractionsprecipitated from solution by means of solvents at low temperatures willbe considered an asphalt or asphaltic material as well as the hardasphalt or substantially pure bitumen separated from the oilin the rststage at atmospheric temperature. Such asphaltic material recovered inthe second stage may be considered a secondary asphalt or a pseudoasphalt. It is of light brown color and of about road oil consistency.

If ythis, process is operated on a waxy oil, the wax will precipitatewith the viscous oil fractions in the second stage depending on thetemperature at which the second precipitation is accomplished.

With the above discussion in mind, it will be perceived that it is anobject of my invention to by means of a solvent in a plurality ofstages, the first stage or stages being operated at a higher temperaturethan the second or subsequent stages.

It is a further object of my invention to separate asphalt from oils bymeans of solvents in two stages wherein a substantially hard asphalt is4precipitated and separated inthe iirst stage and a soft asphalt isprecipitated and separated in the second stage, the precipitation andseparation in the second stage being carried out at a lower temperatureand pressure than that in the rst' stage.

A further-object of my invention'resides in commingling an asphaltcontaining oil vsubstantially free from wax with. a liquefied normallygaseous hydrocarbon solvent under'pressure sufficient to maintain thevsolvent in a liquid state and at atmospheric temperatures oi' about 70F. to 80 F. to precipitate asubstantially hard asphalt, separating theprecipitated asphalt from the oil solvent vsolution and then reducingthe temperature of the oil solvent solution to approximately 40 F. to 0F. by lowering the pressure to eifect vaporizationl'of a portion of thesolvent and thus precipitate heavy viscous oil fractions or vmalthas orsecondary soft asphalt, separating the latter precipitated'asphalt fromthe oil solvent solution and then separating the 'the liquid propane,through valve 1 into line .2.

'I'he amount of propane introduced into line 2 will depend upon thecharacter voi the oil and the temperatures desired in th second asphaltprecipitator or decanter E Thepmixture of liquid propane and residuum ispassed through turbulence or milling coil l into the iirst decante'r `orasphalt precipitator I where the asphalt in the'topped residuumv isprecipitated andv settles rapidly as a slurryv of substantially purebitumen. or hard asphalt containing some oil and'propane. A pressure ofapproximately 125 lbs. per square,y

meh anda temperature of about '10 'F.'to 80 F.

is m 'the danter s. 'rms pressure smdani, is .www propane imma.

`lire points. passing through mist extractor I8 is sent through2,041,275' in decanter 9. The amount o'i propane intro-` duced into theoil will also depend upon whether itis desired to remove the asphalt `atthe bottom of vdecanter 9 as a liquid fraction, the volumetric ratio ofpropane to oil in decanter 9 will be within a range of OLS-6 to 1,depending upon the` character of the oil and the degree to which itv wastopped. Higher volumetric rations-'will precipitate the asphaltlas aslurryof substantially pure bitumen and propane.

The asphalt precipitated in decanter 9vis withdrawn via line I8controlled by valve II and is forced by pump I2 under pressure throughheating coil I4 where'it is heated to a suiiiciently high temperature tomelt the asphalt and vaporize residual propane. The heated mixture isthen passed through line I5 and iiashed through pressure reduction valveI6 on line I5 into evaporator Il which operates at a lower pressure.Superheated steam is introduced into the evaporator I1 throughperforated pipe I8 to supply additional heat and to reduce the asphaltto the proper specification, generally only as regards flash and Theoverhead from evaporator I1 sent through line 33 controlled by valve to.

storage tank 335.

The over-flow from decanter 9 consisting of propane and oil free fromhard asphaltv` and also wax but `containing heavy viscous oil fractions,tars, maltha or pseudo asphaltic material is sent through line36` andpressure reduction valve 31 kinto the vsecond `decanter or asphaltprecipitator 38. In decanter 38 sufficient propane vaporizes to reducethe temperature of the remaining material to a suiliciently lowtemperature Y which causes the aforementioned heavy viscous oilfractions and the like to precipitate from solution. The desired lowtemperature is obtained by controlling the pressure in decanter 38 bythe proper operation of valve 48 on 'line 38 and compressor 28 which isconnected to the decanter by lines 21 and 39. The pressure to bemaintained iny decant-er 38 will generally be about 0 to 25 lbs. gaugewhich corresponds to a temperature of ap- Q proximately between -40`F.to 0 F. As the :propane solution passes through'valve 31, its

88 and run downto propane storage tank 4'. An

equilibrium line 4I controlled 4by valve 42 connects the decanter 9 withthe highpressure stor- The material precipitated in decantersettlestothe bottom of 'the decanter and isy removed lby line 43 controlled byvalve 44 and pump 45 as a mixture of v.propane and heavy viscous oilfrac'- tions and asphaltic material which was not separated in the ilrstdecanter 9., Due to the light character of the material precipitated indecanter 38, sufficient settling time must be provided to .theasphalti'c material to stratify from the solution oi oil and propane. Ifdesired, decanter 38 may be operated` as a chilling column withouteffecting settling of the precipitated material. The chilled mixture maythen be passed to a plurality of settling chambers operated alternatelywhen sufcie'nt time may be provided to permit the precipitated asphalticmaterial to settle or stratify from the-oil'solvent solution. Theprecipitated asphaltic material may then be removed from the bottom ofthe settling chamber as a product substantially free from thelubricating oil fractions.

Pump 45 forces the mixture settling at the bottom of decanter 38underpressure through heat ing coil 46 where it is heated toasufficiently high temperature to render the precipitated material fluidand to vaporize residual propane. The heated mixture is then passed intoline 41 and ilashedthrough pressure reduction valve 48 on line 41 into'evaporator 58 which operates at a lower pressure. Superheated steam isintroduced into evaporator 58 through perforated pipe 5I for supplyingadditional heat and to reduce the asphaltic and viscous heavy oilfractions to a proper speciilcation, such as flash and re points. Theoverhead from evaporator 58 passing through mist extractorl 52 is sentthrough line 53 to cooler 54 and then to separator 55. Theuncondensed'propane from separator55 is sent through line k56 controlledby valve 51 to lines 25, 28 and 21, t'o the 4suction of compressor 28,where its pressure is raised to that in the high pressure systemand issent via line 29 to cooler 38 where it liquefies and runs down intopropane storage tank 4. ny condensed light oil inseparator 55 isWithdrawn through line 58 and condensed water throughline 59. Thelpseudo asphaltic material or heavy viscous oil fractions is taken fromthe bottom 'of evaporator 58 and sent throughv line 68 controlled byvalve 6I to storage tank 62.

The over-ilow from decanter 38 consisting of propane and oil free fromasphalt and heavy viscous oil fractions, malthas and the like and alsowax is sent through line 85 by pump 66 and thenthrough line 61controlled by valve 68 to acid treatment and neutralization with alkali,valve 18 on line 68 being closed. If desired, valve 58 on line` 81 maybe closed and valve 18 on line 58 opened so that the over-flow fromdecanter 38 may Dass into line 88 and then through valve 18 intoevaporator or heater 1I provided with mist extractor 12 where thepropane present is vaporized bythe aid `oi? steam circulated through theclosed steam coil 13. The vaporized propane -passes out o! the heaterthrough line 14 controlled by valve 15 and then passes through cooler 16into lines 18 and 21, to compressor 28, cooler 38 into storage tank 4.'Ihe depropanized oil passes from heater 1I by means of line 18controlled by valve I8 into storage tank 8|. This oil will comprise alubricating oil of low Conradson carbon value and `vill be substantiallyfree from heavy viscous oil fractions, wax and asphalt. The oil may beacid and alkali-treated prior to its use or may be treated by othermethods now conventional. If desired, the over-flow from decanter 38 maybe acid and alkali treated in the 'presence of propane under pressureprior to depropanization in heater 1I.

It is to be understood that the above is merely illustrative ofpreferred embodiments of my invention of which many variations may bemade by those skilled in the art\without departing from the spiritthereof.

I claim:

1. A process for the separation of asphalt from oil which comprisescommingling said oil with a liquefied normally gaseoushydrocarbonsolvent to precipitate asphalt, 'removing the precipitatedasphalt from the oil and solvent, chilling the oil and solvent toprecipitate a .further quantity of asphalt and removing said secondprecipitated asphalt from the oil and solvent.

2. A process as in claim 1 in which the liqueed normally gaseoushydrocarbon solvent contains a substantial proportion of propane. l

3. A process for separatingasphalt from oils containing thesame butwhich are substantially free from Wax which comprises mixing said oilwith a .liquefied normally gaseous hydrocarbon solve'nt andprecipitating the asphalt from the oil and solvent in a plurality o fstages.

4. A process for separating asphalt from oilsv containing the same butwhich are substantially free from wax which comprisesmixing said oilwitha liquefied` normally gaseous hydrocarbon solvent to precipitateasphalt, separating said precipitated asphalt from the oil solventsolution and chilling said oil solvent solution to precipitate furtherquantities oi.' asphalt andseparating said second precipitated asphaltfrom the oil solvent solution. v

5. A process for separating asphalt from oils containing the same butwhich are substantially ing operated at a higherl temperature andpressure than the second of said stages whereby a jtion of the prpaneand thus chill the oil to substantially hard asphalt is precipitated insaid rst stage and a substantially soft asphalt is precipitated in saidsecond stage.

- 7. A process for separating asphalt from oils containing the same butwhich are substantially free from wax which comprises mixing said oilwitha liquefied normally gaseous hydrocarbon solvent underSup'eratmospheric pressure to precipitate asphalt, separating saidprecipitated asphalt from the oil solvent` solution and reducing thepressure on said oil solvent solution to vaporize a portion of thesolvent'to`chi1l the oil and precipitate further quantities of asphalticmaterial and separating said further quantities of precipitatedasphaltic material from the oil solvent solution.

8. A process forseparating asphalt from oils containing the same butwhich are substantially free from Wax which comprises mixing said oilwith liquid propane under pressure suiilcient to maintain said propaneliquid to precipitate asphalt, separating said precipitated asphalt fromthe oil and propane solution, releasing the pressure on the oil andpropane to vaporize a porprecipitate further quantities of asphalt,separating said further quantities of precipitated asphalt from the oiland propane and separating the propane from the oil.

9. A process for separating asphaltfrom pils containing the same butwhich are substantially free from wax which comprises mixing said oilwith propane under pressure suflicient to maintain the propane liquid toprecipitate a substantially hard asphalt and atsubstantially/'atmospheric temperature, separating said precipitatedhard'asphalt from the oil propane solution, reducing the pressure on theoil propane solution to Vaporize a portion of the propane and thus chillthe oil to precipitate a soft asphalt, separating said precipitated softasphalt from the oil and remaining propane and separating the remainingpropane from the oil.

